The present invention relates to a new and distinct cultivar of Begonia, of the family Begoniaceae, and given the cultivar name, ‘TNBEGDY’. Begonia ‘TNBEGDY’ is a tuberous Rex hybrid involving breeding lines using Begonia Rex, Begonia tuberhybrida, and Begonia boliviensis. The new cultivar originated from controlled cross of Begonia ‘MY’, as the seed parent, and Begonia B52-07, as the pollen parent. Both parents are proprietary seedlings.
This selection is uniquely characterized by:                1. attractive dark and patterned foliage,        2. numerous large yellow flowers,        3. continuous bloom time,        4. a trailing habit, and        5. excellent vigor.        
Compared to Begonia ‘Apricots and Lemons’, an unpatented plant, the new cultivar has darker foliage and single rather than double flowers.
Compared to Begonia Bon Bon Series, unpatented plants using Begonia boliviensis breeding, the new cultivar has larger flowers and darker leaves.
The new variety has been reproduced only by asexual propagation (leaf and stem cuttings and tissue culture using growing tips). Each of the progeny exhibits identical characteristics to the original plant. Asexual propagation by micropropagation as done in Canby, Oreg., shows that the foregoing characteristics and distinctions come true to form and are established and transmitted through succeeding propagations. The present invention has not been evaluated under all possible environmental conditions. The phenotype may vary with variations in environment without a change in the genotype of the plant.